Sulfur containing organosilicon compounds are useful as reactive coupling agents between rubber and silica fillers providing for improved physical properties. They are also useful as adhesion primers for glass, metals and other substrates.
Conventionally, organosilicon coupling agents are dispersed on the surface of fillers for use in rubber. The most common filler is carbon black. Dispensing organosilicon coupling agent on the surface of precipitated silica is also known. Generally, this process is achieved either during the mixing of the silica, rubber and coupling agent or a process where the silica powder and the coupling agent are blended together prior to addition of the rubber compound. Unfortunately, such methods result in unequal distribution of silane on the surface of the silica and lack of uniformity in properties when used in rubber.
The present invention relates to a process for the modification of the surface of a silica with a silane compound comprising mixing an aqueous suspension of precipitated silica particulates with a silane compound which is dissolved in an organic solvent, in the presence of a phase transfer catalyst. The present invention also relates to the product of its claimed process.